Metro spokeswoman Carolina Mendoza said several arrests were made during the sweep, but details and charges filed were not immediately available.

Bag searches

Riders can expect bag searches when officers have probable cause, Mendoza said. Authorities will also conduct K-9 sweeps and look for "aberrant behaviors" that could identify potential terrorists, officials said.

Metro Police Chief Victor Rodriguez said the TSA's role in the sweep Friday was limited, with no TSA officials on buses.

"TSA was present to bolster the uniform presence on the (transportation) system," he said. "They provided behavioral detection officers who are specially trained to identify aberrant behaviors that may indicate potential terrorist activity."

More sweeps planned

Rodriguez said more sweeps planned in the next 60 to 90 days.

The routes, Rodriguez said, "are chosen based on crime data and trends and information derived from employees (operators) and bus patrons." He declined to identify them.